Recruitment of new blood vessels (angiogenesis) is required for tumor growth and metastasis. Therefore, the development of angiogenesis inhibitors represents a new approach that may increase the effectiveness of existing cancer treatments. Runt family genes (Runx1,2,3) are transcription factors that playa key role in vascular development including endothelial cell (EC) migration and stem cell recruitment to promote angiogenesis. Runx DNA binding is enhanced by association with the product of the Cbf gene which forms a trimeric DNA binding complex whose 3-dimensional (3D) structure has recently been determined. Computer-aided rational drug design (CADD) can be used to identify chemical compounds with the potential to become therapeutic agents. CADD database searching involves screening of a 3D chemical database to select small molecules that "fit" in the binding site of interest on the target biomolecule. The identified small molecules are then obtained and subjected to experimental assays to select those with the appropriate biological activity. Use of a database of commercially available compounds avoids the need for chemical synthesis, thereby facilitating the identification of active compounds. Our hypothesis is that specific inhibition of Runx-mediated transcriptional activation will inhibit EC migration and angiogenesis. Our goals are to use CADD, in combination with the available 3D structure of Runt to identify compounds with a high potential to bind selectively to Runt. Both the DNA and Cbf binding regions of Runt will be individually targeted. The selected compounds will be obtained and subjected to experimental testing using assays to identify compounds with the desired Runt-binding activities to verify that they are Runt-specific antagonists. An EC migration assay will then be used to screen candidate compounds for biological activity. These approaches are one of the first attempts to inhibit angiogenesis via transcriptional targeting. Since inhibiting Runx transcriptional activity should reduce angiogenesis, the growth of both hematopoietic and solid tumors that depend on a blood supply for survival and growth will be inhibited. The lead compounds developed from this application could also find utility in non-cancer situations, such as macular degeneration, atherosclerosis, or diabetic retinopathy, where uncontrolled angiogenesis is responsible for the pathology.